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Preparation method and application of thin-layer nano flaky total-silicon molecular sieve for preparing caprolactam

An all-silicon molecular sieve and nano-sheet technology, applied in the direction of silicon oxide, silicon dioxide, etc., can solve the problems of complex process, low conversion rate, and easy volatility, so as to reduce coking deactivation, improve catalytic activity, and reduce environmental pollution Effect

Active Publication Date: 2015-01-28
TAIYUAN UNIV OF TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] In ACS Catal. 2011, 1: 337, Ryoo et al reported the use of asymmetric double-headed ammonium surfactant [C 16 h 33 -N + (CH 3 ) 2 -C 6 h 12 -N + (CH 3 ) 2 -C 6 h 13 ](OH) - 2 A single-layer sheet-like hierarchical porous all-silicon molecular sieve with a b-axis thickness of 2 nm was synthesized for gas phase Beckmann rearrangement reaction, WHSV=3 h -1 , the reaction temperature is 350 ℃, the initial conversion rate is 85%, and it drops to 65% after 100 h. The activity and stability of the catalyst are much higher than that of large particle all-silicon molecular sieves, but compared with the existing industrial application level, the conversion rate is relatively low. Low; in addition, the use of toluene and acetonitrile with high toxicity and cost as solvent synthesis template is unfavorable for industrialized large-scale production: the harm of toluene to human health includes irritation to the skin and mucous membranes, and anesthesia to the central nervous system. effect
Acetonitrile is extremely volatile and is a moderately toxic substance that is extremely harmful to the human body, and the discharge of waste liquid can cause serious environmental pollution; using anion exchange resin to exchange bromine-type template agent to obtain hydrogen-oxygen-type template agent, the process is complicated and the cost is high
Currently disclosed patents and documents do not use the very low toxicity of green chemicals dimethyl carbonate, diethyl carbonate and ethanol, propanol as a solvent to synthesize bromine-type, chlorine-type asymmetric double-headed ammonium surfactants, and directly use Synthesis of thin-layer nanosheet silicalite-1 molecular sieves with bromine-type and chlorine-type templates

Method used

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  • Preparation method and application of thin-layer nano flaky total-silicon molecular sieve for preparing caprolactam
  • Preparation method and application of thin-layer nano flaky total-silicon molecular sieve for preparing caprolactam
  • Preparation method and application of thin-layer nano flaky total-silicon molecular sieve for preparing caprolactam

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] a. Add 51.6 g of tetramethylhexamethylenediamine, 337 ml of dimethyl carbonate, and 33.3 g of bromooctadecane into a flat-bottomed flask, heat under reflux in a water bath at 50°C for 8 hours while stirring, cool to room temperature, and filter , washed with dimethyl carbonate for 1-2 times, and air-dried to make an intermediate; add 50.5 g of the intermediate, 300 ml of ethanol, and 49.5 g of bromohexane into a flat-bottomed flask, and heat under reflux in an oil bath at 79 °C under stirring 10 hours. After completion, heat up to 85°C, stir and dry to obtain a light yellow translucent solid, cool to room temperature, wash with ether 1-2 times, and obtain template C 18-6-6 Br 2 , the yield is 99%.

[0043] b. Add 4.98 g of ethyl orthosilicate to 3.83 g of tetramethylammonium hydroxide, stir at room temperature for 10 minutes, then add 17 g of deionized water, 2.5 g of ethanol, and 0.85 g of the template prepared in step a above C 18-6-6 Br 2 , after stirring evenly...

Embodiment 2

[0047] a. Add 86 g of tetramethylhexamethylenediamine, 500 ml of diethyl carbonate, and 39 g of docosane bromide into a flat-bottomed flask, heat under reflux in a water bath at 55 °C for 5 hours under stirring, and cool to room temperature. Centrifuge, wash with diethyl carbonate for 1-2 times, air-dry to make the intermediate; add 56.1 g of the intermediate, 300 ml of ethanol, and 33 g of bromohexane into a flat-bottomed flask, and reflux in an oil bath at 79 °C while stirring Heat for 10 hours. After completion, heat up to 85°C, stir and dry to obtain a yellow translucent solid, cool to room temperature, wash with ether 1-2 times, and obtain template C 22-6-6 Br 2 , the yield is 99.2%.

[0048] b. Add 4.98 g of ethyl orthosilicate to 1.28 g of tetramethylammonium hydroxide, stir at room temperature for 15 minutes, then add 14.40 g of deionized water, 2.5 g of ethanol, and 0.78 g of the template prepared in step a above C 18-6-6 Br 2 , after stirring evenly, heat in a w...

Embodiment 3

[0051] a. Add 51.6 g of tetramethylhexamethylenediamine, 350 ml of dimethyl carbonate, and 24.9 g of dodecane bromide into a flat-bottomed flask, heat under reflux in a water bath at 45 °C for 10 hours while stirring, cool to room temperature, and centrifuge , washed 1-2 times with dimethyl carbonate, and air-dried to make an intermediate; add 42.1 g of intermediate, 300 ml of propanol, and 20.55 g of bromobutane into a flat-bottomed flask respectively, and reflux in an oil bath at 85 °C while stirring Heat for 8 hours. After completion, heat up to 90°C, stir and dry, cool to room temperature, and wash with ether 1-2 times to obtain template C 12-6-4 Br 2 , the yield is 99.3%.

[0052] b. Add 4.98 g of ethyl orthosilicate to 1.28 g of tetraethylammonium hydroxide, stir at room temperature for 8 minutes, then add 18.90 g of deionized water, 2.5 g of ethanol, and 0.69 g of the template prepared in step a above C 12-6-4 Br2 , after stirring evenly, heated in a water bath at 6...

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Abstract

The invention relates to a preparation method of a thin-layer nano flaky total-silicon molecular sieve for preparing caprolactam. The preparation method comprises the following steps: uniformly stirring a silicon source and an alkali source to obtain a mixture I; dissolving a template agent in a mixed solution of deionized water and ethanol to obtain a mixture II, and gradually dropwise adding the mixture I into the mixture II to be stirred to obtain a mixture III, and stirring the mixture III in a water bath to obtain initial gel; dynamically crystallizing the initial gel in a closed reaction kettle, and washing and drying the initial gel to obtain the thin-layer nano flaky total-silicon molecular sieve. The preparation method has the advantages of low cost, small energy consumption, high conversion rate, no pollution and capability of realizing industrial production.

Description

technical field [0001] The invention belongs to the preparation of molecular sieves, and in particular relates to a preparation method and application of a thin-layer nano-flaky all-silicon Silicalite-1 molecular sieve prepared from caprolactam. Background technique [0002] Caprolactam is an important intermediate used in the synthesis of nylon-6 fibers and resins, and is widely used in artificial leather, medicine, and chemical additives. In 2010, the domestic self-sufficiency rate of caprolactam was 43.9%, and the amount of imported caprolactam in my country increased by an average of 12% per year. The domestic production capacity is insufficient, and a large number of imports are relied on. [0003] At present, caprolactam is mainly synthesized by Beckmann rearrangement reaction of cyclohexanone oxime. There are two main processes to realize this process: liquid-phase Beckmann rearrangement and gas-phase Beckmann rearrangement. Since the liquid-phase Beckmann rearrangem...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/12
Inventor 李晓峰葛超刘晓臻窦涛
Owner TAIYUAN UNIV OF TECH
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